Understand Your Score

Both tasks are scored on real geographic coordinates. Your drawing is never moved, rotated or resized to fit the answer: if you draw the right shape in the wrong place, the score says so.

Regions: overlap

Your rings are combined into one shape and the parts over the sea (or large lakes) are removed. The shape is then compared with the real land area of the region:

overlap = area(yours ∩ real) ÷ area(yours ∪ real)

An overlap of 1 means a perfect match. Drawing too small lowers the top half of the fraction; drawing too big, or over a neighbour, raises the bottom half. Because freehand drawing is hard, the overlap is mapped onto a friendlier scale: an overlap of 0.5 scores 50, 0.7 scores 75, 0.85 scores 90 and 0.95 or more scores 100.

The result panel also shows how much of the region you covered and how much extra you drew, as a share of the region’s area.

Borders: accuracy and coverage

Your line and the real border are both sampled every few hundred metres. For each of your points we measure the distance to the real border; for each point of the real border, the distance to your line. A point counts fully inside the tolerance and fades to nothing at three times the tolerance.

• On the line (precision): the share of your drawing that lies along the real border.
• Border covered (recall): the share of the real border that your drawing follows.

The score is the harmonic mean of the two, times 100. A short, perfect stroke has high precision but low coverage; a scribble across the whole map has high coverage but low precision. Both score poorly. Drawing the same correct stretch several times does not help.

The tolerance depends on the size of the question: about 1.2% of the viewport’s diagonal, between 2 km and 25 km. A prefecture border gets 3–5 km; the US–Canada border gets the full 25 km. The tolerance is shown on every result.

Sea, lakes and islands

• Anything you draw over the sea is ignored in both modes, so coastlines never need to be precise.
• Drawing over a neighbouring region’s land does count against you.
• Regions are scored on their main land parts; islands smaller than a tenth of the largest part are shown on the reveal but not scored. Very small countries are not asked as outlines.
• Border questions are only asked for pairs that share a land border; a strait does not count.

Time

In the daily challenge each round has 30 seconds, counted from when the map has finished loading. When time runs out your drawing is submitted as it is. Practice is untimed. Time never changes the score itself.

Versions

Every result records the scoring version (currently area-1 and border-1) and the data version of the pack. If the rules or the boundaries change, old results keep their original meaning and new puzzles use the new rules; a finished daily puzzle is never re-scored.